Treatment variation in acute management of patients with aneurysmal subarachnoid hemorrhage: a multicenter case vignette study

Although a landmark randomized controlled trial (RCT) compared clipping with coiling in aneurysmal subarachnoid hemorrhage (aSAH), real-world practice remains heterogeneous. Advances in endovascular and microsurgical techniques, complex or borderline cases not well represented in trials, and differences in institutional expertise likely contribute to between-center variation. Understanding these treatment preferences is critical for identifying potential unwarranted variation and designing comparative effectiveness research that reflects decision-making. A multicenter case-vignette study was conducted across five Dutch tertiary referral centers for aSAH (n=16 specialists) between May and October 2025. Fifteen real-world aSAH vignettes, representing diverse clinical and radiological profiles, were systematically presented during live meetings of the local neurovascular multidisciplinary teams (MDT), including neurologists, neurosurgeons, and interventional-radiologists. For each case, MDTs proposed an aneurysm treatment strategy. Between-center variation was quantified using Fleiss’ κ with 95% confidence intervals (CI). Of 15 case vignettes, agreement on aneurysm treatment strategy among at least four of five centers was reached in 12 cases (80%). Regarding treatment modality, at least four of five centers opted for a similar modality in 10 of 11 cases (91%). The proportion of clipping versus any endovascular treatment option ranged between centers from 2/12 aneurysm treatments proposals (17%) to 8/13 proposals (62%), resulting in moderate agreement (κ = 0.49, 95% CI 0.31-0.68) for between-center variation. There is between-center variation in treatment strategies for ruptured intracranial aneurysms across Dutch tertiary referral centers for aSAH in identical case vignettes. These case-mix independent, center-level preferences may be leveraged for comparative effectiveness research. • In a multicenter case-vignette study of identical aneurysmal subarachnoid hemorrhage scenarios, substantial between-center variation in aneurysm treatment modality persisted despite overall agreement on the need for intervention. • The proportion of microsurgical clipping ranged from 17% to 62% across tertiary referral centers, resulting in only moderate between-center agreement. • These case-mix–independent institutional preferences provide a pragmatic foundation for comparative effectiveness research when randomized trials are difficult to conduct.